Hi all. 

I got at big problem regarding I2C communication with the MPU6050. 

I seem to have tried everything but it just wont work. The protocol can be found at: 

http://invensense.com/mems/gyro/documents/PS-MPU-6000A.pdf  (page 37)

The problem is that  I2C_1_MasterSendStart(devAddr, I2C_1_WRITE_XFER_MODE) returns I2C_MSTR_ERR_LB_NAK ??? Which I dont understand. 

Here's my souce code: 

void main(){

    uint8 wrData;
    uint8 rdData;
    uint8 status; 
    uint8 readFlag;
    uint8 breakp; 
    uint8 masterStatus; 

    I2C_1_Start();

    wrData = 117;   //Reg number
    uint8 devAddr = 0b110100;

    for(;;){

        status = I2C_1_MasterSendStart(devAddr, I2C_1_WRITE_XFER_MODE); 

        if(status == I2C_1_MSTR_NO_ERROR){         /* Check if transfer completed without errors */

            status = I2C_1_MasterWriteByte(wrData);   
       }

       I2C_1_MasterSendStop();    /* Send Stop */

      status = I2C_1_MasterSendStart(devAddr, I2C_1_READ_XFER_MODE);

       if(status == I2C_1_MSTR_NO_ERROR) {         /* Check if transfer completed without errors */

  rdData = I2C_1_MasterReadByte(I2C_1_NAK_DATA);

    }

    I2C_1_MasterSendStop(); /* Send Stop */

    }

}

Now problem is the if's are always going false because of the status :( .. 

Any help pls?

1.Try using I2C_MasterClearStatus() frist before the write/read

2. It would be helpful if you can post the project up here.   

You are still using the wrong address, it must be 0x68.

Bob

Sorry, too fast.

You are defining a 6-bit binary value and rely on the compiler that it will insert it into the "right" places. If this would work right now this is hazardous when the compiler got changed / updated.

The Datasheet tells to take the given bit-pattern and to append 1 bit from the hard-wired A0 input, so we have got 7 bits already and that is our complete slave address, the rest is handled by I2C. so we come to 0b01101000 which is 0x64 if I am not mistaken.

Bob

The I²C address seems to be wrong. You define it as 0b110100, but according to the data sheet it should be 0b1101000 (watch for the additional zero).

Oh - Bob was too fast and I was too slow :(

Do not be dissapointed, you were right too :-)

Bob

Ahh and by the way, I WAS mistaken, it is 0x68 of course!

Math is hard, and binary math double so

Yes, there are 10 different kinds of people, those who understand binary and those who don't.

Bob

To be more OnT: There are two types of people in the world: 1. Those who can extrapolate from incomplete data.

@Texton: can you tell us whether this was the problem or not?